Scala is a functional programming language on the JVM. Hadoop uses a functional programming model to represent large-scale distributed computation. Scala is thus a very natural match for Hadoop.
In this presentation to the San Francisco Scala User Group, Dr. Oscar Boykin and Dr. Argyris Zymnis from Twitter give us some insight on Scalding DSL and provide some example jobs for common use cases.
Twitter uses Scalding for data analysis and machine learning, particularly in cases where we need more than sql-like queries on the logs, for instance fitting models and matrix processing. It scales beautifully from simple, grep-like jobs all the way up to jobs with hundreds of map-reduce pairs.
** For more resources, training, and video tutorials on Scala, head to http://marakana.com/s/tags/scala